<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Canvas 原型进度条</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        body{
            text-align: center;
        }

    </style>
</head>
<body>
    <canvas id="canvas" width="500" height="500" style="background: #000;"></canvas> 
    <script>
        window.onload = function () {
            let canvas = document.getElementById('canvas')
            let context = canvas.getContext('2d'),//创建二维画布
                centerX = canvas.width / 2,
                centerY = canvas.height / 2;
            function blueCircle() {
                context.save() 
                
            }
                
        }
    </script>
</body>
</html>